This invention relates to continuous motion can decorating apparatus in general and relates more particularly to apparatus of this type in which linear mandrel speed and spacing between mandrels greatly exceeds deco chain speed and spacing between pins carried by the deco chain.
Both U.S. Pat. No. 3,766,851, issued Oct. 23, 1973 to E. Sirvet et al. for Continuous Can Printer and Handling Apparatus and pending U.S. Pat. application Ser. No. 07/565,695 filed Aug. 13, 1990 by R. DiDonato et al, now U.S. Pat. No. 5,111,742, entitled Mandrel Trip Assembly for Continuous Motion Can Decorator and assigned to the assignee of the instant invention, disclose relatively high-speed so-called continuous motion can decorating apparatus in which undecorated cylindrical containers mounted on mandrels that are carried by a rotating carrier have decorations applied thereto, have a protective coating of varnish applied over the decorations, and are then delivered to suction holding cups on a rotating transfer wheel from which they are loaded on pins that are carried in a single file arrangement by a so-called deco chain that is moving in a closed loop. The chain path extends through an oven where the pin loaded cans are subjected to heat which acts to cure the materials forming the decorations and their protective coating.
For the most part, in prior art apparatus of this type the mandrels and deco-chain travel generally at the same linear speed and the spacing between mandrels generally equals the spacing between deco chain pins. This type of apparatus has proven to be satisfactory for equipment that decorates the most popular size beverage containers now used in the U.S., the twelve ounce aluminum can having a diameter of 25/8", which apparatus operates at production rates up to about 2000 cans per minute. For a given density loading of the deco chain, as production rates increase this is accompanied by increased deco chain speed. There comes a point where an increase in oven size and a longer chain are required if oven temperature is to be maintained low enough to prevent excessive heating of the cans. Increasing oven size and chain length requires a substantial increase in capital investment, and increasing chain length will also result in increased maintenance costs and more down time.
One prior art approach to possibly solving this problem is found in U.S. Pat. No. 3,469,670 issued Sept. 30, 1969 to W. J. Cartwright for a Can Transfer Mechanism. In this Cartwright patent deco chain speed is much slower than linear mandrel speed and pin spacing is much less than mandrel spacing. This is achieved by constructing the transfer wheel so that containers are received in single file at the periphery of the rotating transfer wheel and are then moved radially inward to form a single file at a position where the linear speed of the container matches chain speed during loading of the pins which are in single file on the chain. During pin loading the spacing between containers is substantially equal to spacing between pins.
Another approach for solving this same problem is to have the deco chain carry two rows of pins, move containers on the transfer wheel suction cups radially inward to reduce linear container speed to match that of the deco chain, and position the containers on the transfer wheel so that alternate containers are received by one row of pins and the remaining containers are received by the other row of pins. In this arrangement, at unloading of the mandrels, mandrel and suction cup speeds are the same, as are spacing between suction cups and spacing between mandrels. Further, at loading of the chain pins, pin spacing in each row equals spacing between the suction cups, and linear suction cup speed equals chain speed.